2 - DNA Structure
Content
TRAITS
TRAITS
ALLELES
Variations of a gene
GENOTYPE
The combination of alleles expressed in your genes
PHENOTYPE
The genetic traits expressed physically
DOMINANT use capital (B)
= an allele that expresses itself stronger than others
RECESSIVE use small letter (b)
= an allele that expresses itself weaker than others
CODOMINANT (Blood AB)
= alleles that both express themselves equally but DON’T
combine
INCOMPLETE DOMINANCE (RW or rw)
= alleles that both express themselves equally but DO
combine
HOMOZYGOUS
= 2 alleles of the same type (BB, bb)
HETEROZYGOUS
= 2 alleles of different types (Bb)
COLOUR BLINDNESS
COLOUR BLINDNESS
WOMAN
XNXN = normal
XNXC = normal but
carrier
XCXC = color blind
XX =
XY =
XN = allele for normal vision
XC = allele for color blindness
XN Y
X
N
X
X
C
XN Y
C
X
C
XC Y
X
MAN
XNY = normal
XCY = color blind
XC Y
X
XC Y
X
COLOUR BLINDNESS
WOMAN
XNXN = normal
XNXC = normal but
carrier
XCXC = color blind
XX =
XY =
XN = allele for normal vision
MAN
XC = allele for color blindness
X Y = normal
Y = color blind
XN Y
XN X Y
XN X XN
XNX
XN N Y XC C XCY
XN X
XNX
XC C XCY XC C XCY
N
C
XC
Y
XC
Y
XC
Y
BLOOD TYPE
A
A
A
A
A
A
A
A
B
A
B
B
A
A
A
A
A
A
A
B
i
i
i
i
BLOOD TYPE
A
A
+
A
A
-
A
O
+
A
O
-
A
A
B
B
+
B
B
-
B
O
+
B
O
-
A
B
+
A
B
-
O
O
+
O
O
-
EYE COLOUR
B = dominant allele for brown
b = recessive allele for blue
b
b
B
B
B
B
B
B
B
b
B
B
B
b
B
b
b
b
b
b
HISTORY OF
GENETICS
• 1865: Mendel discovers the rules of inheritence.
• 1910: Scientists determine that genes reside on chromosomes
• 1944: Scientists suggest genetic material is DNA, not protein results not
accepted.
• 1952: Alfred Hershey and Martha Chase show conclusively that DNA is
genetic material.
• 1953: Watson, Crick, Wilkins, and Franklin determine the structure of DNA.
• 1961: The gentic code is cracked.
• 1990: Human Genome Project begins to map and sequence the entire
human genome.
• 1997: Scientists clone a sheep, ‘Dolly’.
• 2000: Most of the human DNA sequence is completed.
THE HUMAN
GENOME PROJECT
PROJECT
MAP
the 20,000-25,000 genes in human
DNA
(1990 – 2003)
SEQUENCE
the 3 billion chemical base pairs that make up
human DNA
(2006)
STORE
this information in databases available on the internet to everyone
APPLY KNOWLEDGE
APPLY KNOWLEDGE
EARLY
DETECTION
BETTER
MATCH
of diseases
for transplants
DNA
IDENTIFICATI
ON
Crime Scenes
Paternity tests
BIOENGINEERI
NG
BETTER DRUG
DESIGNS
Change plants and
animals to be more
productive and more
nutritious
for diseases
Natural Pesticides
Historia del ADN
Watson and Crick
received the Nobel
prize in 1962.
Why is DNA important ?
DNA genotype is expressed in proteins which
provide the bases for the phenotypical
caracteristics.
GENOTYPE = genetic information found in
DNA
PHENOTYPE = Observable characteristics
Genes DO NOT form proteins directly
GENETIC MATERIAL
GENOME
= sum of all genetic material
CHROMOSOMES
= a single piece of coiled DNA containing many genes
(23 PAIRS)
GENES
a segment of nucleic acid that specifies a trait.
(500 – 4500 per chromosome)
BASE PAIRS
a pair of nucleotides
(50 – 450 million per chromosome)
NUCLEOTIDES
NUCLEIC ACIDS
= long chain of nucleotides
1)DNA
(deoxyribonucleic acid)
-contains the genetic code (the order of
nucleotides)
(the blue prints of an
organism)
DNA Structure
DOUBLE HELIX = two chains of DNA arranged
into a spiral ladder
NUCLEOTIDES = millions of tiny subunits
Each nucleotide consists of:
1. Phosphate group
Phosph
2. Pentose sugar
ate
3. Nitrogenous base
Pento
se
Sugar
Nitrogeno
us
Base
NUCLEOTIDES
BACKBONE of DNA formed from
phosphate and sugar
base
RUNGS formed by bases
There are four types of nitrogenous bases.
NUCLEOTIDES
GATTACA
I
I
I
I
I I
I
NUCLEOTIDES
The building blocks of DNA and
RNA
Only 4 but differ slightly
1) DNA
Guanine
Cytosine
(G
Adenine
(A)
G–C
A-T
Thymine (T)
Uracil (U)
2) RNA
Pairs of nucleotides
(C)
PYRAMIDIN
E
= 1 ring
PURIN
E
=2
rings
BASE PAIRS
G–C
A-U
Nucleotides
A
Adenine
T
Thymine
C
G
Cytosine
Guanine
H bonds
= weak bonds that join nucleotides
A-T 2 H bonds
G-C 3 H bonds
COMPLEMENTARY BASE PAIRING
the order of the bases in one strand
determines the order of the bases in the
other strand.
A
T
C
T
G
A
C
A
G
T
C
G
T
A
DNA’S GENETIC CODE
To crack it we need to look at the sequence
of bases.
CODONS = arrangement of bases in triplets
AGG-CTC-AAG-TCC-TAG
TCC-GAG-TTC-AGG-ATC
DNA
Gene
CGAT
1) DNA
REPLICATION
Separation
CGATATGCAAGGCC
TT
GCTATAGCTTCCGG
AA
Replication
CGATATGCAAGGCC
GCTATAGCTTCCGG
TT
AA
CGATATGCAAGGCC
TT
GCTATAGCTTCCGG
AA
Makes more DNA
2) PROTEIN
SYNTHESIS
Transcription
RN
GCUA
A
Translati
on A.A.
Protei
TRAIT
GENE
(Unique sequence of DNA
nucleotides)
Sequence of RNA nucleotides
Sequence of A.A.
Unique Protein
TRAIT or PHENOTYPE
Semi-Conservative Model
Semi-Conservative Model
5´
3´
3´
A
C
T
3´
5´
G
5´
DNA vs RNA Structure
DNA
RNA
Chains
2
1
Sugar
Deoxyribose
Ribose
Pyramidines
Thymine, Cytosine
Uracil, Cytosine
Purines
Adenine, Guanine
Adenine, Guanine
FUNCTION OF
RNA
TRANSCRIPTION:
Transference of
genetic info from
DNA to RNA
NUCLEU
S
CYTOPLAS
M
TRANSLATION:
Transference of info
from RNA to
proteins
TRANSCRIPTION
1. An enzyme separates the DNA strands,
creating a “bubble” to permit copying
2. RNA puts necessary nucleotides to form a
molecule of Messenger RNA (mRNA)
3. Match up of:
T with A
G with C
A with U
4. Segment of DNA is copied and mRNA leaves
nucleus
THE GENETIC CODE
1961 – first a.a. codon discovered
UUU – PHENYL ALANINE
AUG – produce Methionone and START codon
UAA, UAG and UGA – signal to stop Translation
GENETIC CODE (mRNA)
C
A
G
UUU (Phe)
UCU (Ser)
UAU (Tyr)
UGU (Cys)
UUC (Phe)
UCC (Ser)
UAC (Tyr)
UGC (Cys)
UUA (Leu)
UCA (Ser)
UAA (STOP)
UGA (STOP)
UUG (Leu)
UCG (Ser)
UAG (STOP)
UGG (Trp)
CUU (Leu)
CCU (Pro)
CAU (His)
CGU (Arg)
CUC (Leu)
CCC (Pro)
CAC (His)
CGC (Arg)
CUA (Leu)
CCA (Pro)
CAA (Gln)
CGA (Arg)
CUG (Leu)
CCG (Pro)
CAG (Gln)
CGG (Arg)
AUU (Ile)
ACU (Thr)
AAU (Asn)
AGU (Ser)
AUC (Ile)
ACC (Thr)
AAC (Asn)
AGC (Ser)
AUA (Ile)
ACA (Thr)
AAA (Lys)
AGA (Arg)
AUG (Meth / START)
ACG (Thr)
AAG (lys)
AGG (Arg)
GUU (Val)
GCU (Ala)
GAU (Asp)
GGU (Gly)
GUC (Val)
GCC (Ala)
GAC (Asp)
GGC (Gly)
GUA (Val)
GCA (Ala)
GAA (Glu)
GGA (Gly)
GUG (Val)
GCG (Ala)
GAG (Glu)
GGG (Gly)
U
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
Amino Acid
Abbreviation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Alanine
Arginine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Serine
Threonine
Tryptophan
Tyrosine
Valine
Ala
Arg
Asn
Asp
Cys
Glu
Gln
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Ser
Thr
Trp
Tyr
Val
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
TRANSLATION
1. mRNA binds to a ribosome and begins to
interpret the message
2. mRNA information is read in groups of three
letters = CODON
3. transfer RNA (tRNA) binds to each codon of
mRNA
has corresponding ANTICODON
other side has A.A. which joins to form
proteins at ribosome
The information of the messenger RNA (mRNA)
describes which amino acids should be in the
protein chain.
A molecule of transfer RNA (tRNA) will carry in
the proper amino acid, one at a time.
A
A.
m
R
N
A
Amino acid
m
R
N
A
A different set of three mRNA subunits means a different
tRNA molecule. That means a different amino acid will be
Carried in.
Two different
Amino acids
Two different tRNA molecules
m
R
N
A
The next tRNA will
Carry in the proper
amino acid
and the process will
continue.
The chain of amino acids is
called a ‘polypeptide’
And when it is very long it is
called a protein.
polypeptide
A polypeptide chain
• Even this is a very, very short polypeptide chain.
Most have hundreds or thousands of amino acids.
A very short polypeptide chain, or part of a protein
DNA thread
TRANSCRIPTION
RNA
Codon
TRANSLATION
Polypeptide
Amino acid
TYPES of RNA
NAME
FUNCTION
Messenger
RNA (mRNA)
Copies info from DNA and takes info
to ribosome
Transfer RNA
(tRNA)
Translates messages from mRNA and
has a complementary codon =
ANTICODON and carries
corresponding a.a.
Ribosomal RNA
(rRNA)
RNA entangled with proteins which
serves as an anchor for translation
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
DNA
A polymer made of
MONOMERS called
Is formed from:
Is made by an P
ENZYME called
R
SUMMARY
N
RNA
There are
3 TYPES called
Happens in a
ORGANELLE called
And with proteins they form
PROTEINS
POLYMER formed from
MONOMERS called
ENZYMES
= biological catalyst
Usually end in
–ASE
( e.g. primase, polymerase, etc)
CATALYST = substance that speeds up a reaction
DNA info
= 6 billion nucleotide pairs
= 1400 biology textbooks
copied in a few hours because of enzymes
Therefore, many enzymes and proteins needed.
DNA REPLICATION
ORGIN OF REPLICATION (OR)
= short specific sequence of DNA nucleotides where
replication of a chromosome begins
=
Recognized by proteins that initiate replication
separates strands and opens replication bubble
DNA replicated in both directions
Thousands of OR bubbles open at same time
strands eventually fused
DNA REPLICATION
REPLICATION FORKS
= Y shaped region at end of bubble where parental strands of DNA are
unwound
Helicase
untwists double helix at replication
Separates parental strand
Topoisomerase
Relieves strain by breaking, swivelling and rejoining DNA strands
Primase
Synthesizes short RNA primer used to begin DNA synthesis
DNA Polymerase III
Elongates primer and then existing chain by adding
nucleotides in 5´ to 3´ direction to complete new DNA
LEADING STRAND
= strand elongated continuously from primer towards fork
LAGGING STRAND
= strand elongated discontinuously away from fork
each has a primer
OZAKI FRAGMENTS
= segments of lagging strands
DNA Ligase
joins Ozaki fragments
TRANSCRIPTION
1) RNA Polymerase
•separates 2 DNA strands
•joins RNA nucleotides in 5´ to 3´direction complementary to
DNA
doesn´t need primer
PROMOTOR Signals where transcription begins
TERMINATOR Signals where transcription ends
TRANSCRIPTION UNIT area transcribed
TRANSCRIPTION
RNA SPLICING
= interspersed coding regions are removed from long regions of
noncoding regions
= cut and paste
EXONS - coding regions later translated into a.a.
INTRONS – noncoding regions between coding regions
SPLICEOSOME – complex that cuts out introns and puts
them together
RIBOZYMES – RNA that functions as enzymes
e.g. some introns, ribosomes
MUTATIONS
= changes to genetic information of a cell
GENETIC DISORDER
= if mutation has adverse affect on phenotype
SUBSTITUTION = replacement of one nucleotide
a) SILENT MUTATION
a.a. does NOT change no effect
b) MISSENSE MUTATION
a.a changes to another no effect or new trait
c) NONSENSE MUTATION
change to STOP codon non-functional protein
INSERTIONS and DELETIONS
FRAMESHIFT disastrous non-functional protein
DNA MUTATIONS
If a mutation in the DNA strand :
•1) changes the base in position 9 to a C
how would this affect the protein ?
•2) changes the base in position 5 to a T
what will the sequence be ?
•3) eliminates the first codon
Which protein will be produced
• 4) eliminates the last codón, what would happen ?
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
TRANSLATION
Initiation
Enlongation
Termination
TRAITS
ALLELES
Variations of a gene
GENOTYPE
The combination of alleles expressed in your genes
PHENOTYPE
The genetic traits expressed physically
DOMINANT use capital (B)
= an allele that expresses itself stronger than others
RECESSIVE use small letter (b)
= an allele that expresses itself weaker than others
CODOMINANT (Blood AB)
= alleles that both express themselves equally but DON’T
combine
INCOMPLETE DOMINANCE (RW or rw)
= alleles that both express themselves equally but DO
combine
HOMOZYGOUS
= 2 alleles of the same type (BB, bb)
HETEROZYGOUS
= 2 alleles of different types (Bb)
COLOUR BLINDNESS
COLOUR BLINDNESS
WOMAN
XNXN = normal
XNXC = normal but
carrier
XCXC = color blind
XX =
XY =
XN = allele for normal vision
XC = allele for color blindness
XN Y
X
N
X
X
C
XN Y
C
X
C
XC Y
X
MAN
XNY = normal
XCY = color blind
XC Y
X
XC Y
X
COLOUR BLINDNESS
WOMAN
XNXN = normal
XNXC = normal but
carrier
XCXC = color blind
XX =
XY =
XN = allele for normal vision
MAN
XC = allele for color blindness
X Y = normal
Y = color blind
XN Y
XN X Y
XN X XN
XNX
XN N Y XC C XCY
XN X
XNX
XC C XCY XC C XCY
N
C
XC
Y
XC
Y
XC
Y
BLOOD TYPE
A
A
A
A
A
A
A
A
B
A
B
B
A
A
A
A
A
A
A
B
i
i
i
i
BLOOD TYPE
A
A
+
A
A
-
A
O
+
A
O
-
A
A
B
B
+
B
B
-
B
O
+
B
O
-
A
B
+
A
B
-
O
O
+
O
O
-
EYE COLOUR
B = dominant allele for brown
b = recessive allele for blue
b
b
B
B
B
B
B
B
B
b
B
B
B
b
B
b
b
b
b
b
HISTORY OF
GENETICS
• 1865: Mendel discovers the rules of inheritence.
• 1910: Scientists determine that genes reside on chromosomes
• 1944: Scientists suggest genetic material is DNA, not protein results not
accepted.
• 1952: Alfred Hershey and Martha Chase show conclusively that DNA is
genetic material.
• 1953: Watson, Crick, Wilkins, and Franklin determine the structure of DNA.
• 1961: The gentic code is cracked.
• 1990: Human Genome Project begins to map and sequence the entire
human genome.
• 1997: Scientists clone a sheep, ‘Dolly’.
• 2000: Most of the human DNA sequence is completed.
THE HUMAN
GENOME PROJECT
PROJECT
MAP
the 20,000-25,000 genes in human
DNA
(1990 – 2003)
SEQUENCE
the 3 billion chemical base pairs that make up
human DNA
(2006)
STORE
this information in databases available on the internet to everyone
APPLY KNOWLEDGE
APPLY KNOWLEDGE
EARLY
DETECTION
BETTER
MATCH
of diseases
for transplants
DNA
IDENTIFICATI
ON
Crime Scenes
Paternity tests
BIOENGINEERI
NG
BETTER DRUG
DESIGNS
Change plants and
animals to be more
productive and more
nutritious
for diseases
Natural Pesticides
Historia del ADN
Watson and Crick
received the Nobel
prize in 1962.
Why is DNA important ?
DNA genotype is expressed in proteins which
provide the bases for the phenotypical
caracteristics.
GENOTYPE = genetic information found in
DNA
PHENOTYPE = Observable characteristics
Genes DO NOT form proteins directly
GENETIC MATERIAL
GENOME
= sum of all genetic material
CHROMOSOMES
= a single piece of coiled DNA containing many genes
(23 PAIRS)
GENES
a segment of nucleic acid that specifies a trait.
(500 – 4500 per chromosome)
BASE PAIRS
a pair of nucleotides
(50 – 450 million per chromosome)
NUCLEOTIDES
NUCLEIC ACIDS
= long chain of nucleotides
1)DNA
(deoxyribonucleic acid)
-contains the genetic code (the order of
nucleotides)
(the blue prints of an
organism)
DNA Structure
DOUBLE HELIX = two chains of DNA arranged
into a spiral ladder
NUCLEOTIDES = millions of tiny subunits
Each nucleotide consists of:
1. Phosphate group
Phosph
2. Pentose sugar
ate
3. Nitrogenous base
Pento
se
Sugar
Nitrogeno
us
Base
NUCLEOTIDES
BACKBONE of DNA formed from
phosphate and sugar
base
RUNGS formed by bases
There are four types of nitrogenous bases.
NUCLEOTIDES
GATTACA
I
I
I
I
I I
I
NUCLEOTIDES
The building blocks of DNA and
RNA
Only 4 but differ slightly
1) DNA
Guanine
Cytosine
(G
Adenine
(A)
G–C
A-T
Thymine (T)
Uracil (U)
2) RNA
Pairs of nucleotides
(C)
PYRAMIDIN
E
= 1 ring
PURIN
E
=2
rings
BASE PAIRS
G–C
A-U
Nucleotides
A
Adenine
T
Thymine
C
G
Cytosine
Guanine
H bonds
= weak bonds that join nucleotides
A-T 2 H bonds
G-C 3 H bonds
COMPLEMENTARY BASE PAIRING
the order of the bases in one strand
determines the order of the bases in the
other strand.
A
T
C
T
G
A
C
A
G
T
C
G
T
A
DNA’S GENETIC CODE
To crack it we need to look at the sequence
of bases.
CODONS = arrangement of bases in triplets
AGG-CTC-AAG-TCC-TAG
TCC-GAG-TTC-AGG-ATC
DNA
Gene
CGAT
1) DNA
REPLICATION
Separation
CGATATGCAAGGCC
TT
GCTATAGCTTCCGG
AA
Replication
CGATATGCAAGGCC
GCTATAGCTTCCGG
TT
AA
CGATATGCAAGGCC
TT
GCTATAGCTTCCGG
AA
Makes more DNA
2) PROTEIN
SYNTHESIS
Transcription
RN
GCUA
A
Translati
on A.A.
Protei
TRAIT
GENE
(Unique sequence of DNA
nucleotides)
Sequence of RNA nucleotides
Sequence of A.A.
Unique Protein
TRAIT or PHENOTYPE
Semi-Conservative Model
Semi-Conservative Model
5´
3´
3´
A
C
T
3´
5´
G
5´
DNA vs RNA Structure
DNA
RNA
Chains
2
1
Sugar
Deoxyribose
Ribose
Pyramidines
Thymine, Cytosine
Uracil, Cytosine
Purines
Adenine, Guanine
Adenine, Guanine
FUNCTION OF
RNA
TRANSCRIPTION:
Transference of
genetic info from
DNA to RNA
NUCLEU
S
CYTOPLAS
M
TRANSLATION:
Transference of info
from RNA to
proteins
TRANSCRIPTION
1. An enzyme separates the DNA strands,
creating a “bubble” to permit copying
2. RNA puts necessary nucleotides to form a
molecule of Messenger RNA (mRNA)
3. Match up of:
T with A
G with C
A with U
4. Segment of DNA is copied and mRNA leaves
nucleus
THE GENETIC CODE
1961 – first a.a. codon discovered
UUU – PHENYL ALANINE
AUG – produce Methionone and START codon
UAA, UAG and UGA – signal to stop Translation
GENETIC CODE (mRNA)
C
A
G
UUU (Phe)
UCU (Ser)
UAU (Tyr)
UGU (Cys)
UUC (Phe)
UCC (Ser)
UAC (Tyr)
UGC (Cys)
UUA (Leu)
UCA (Ser)
UAA (STOP)
UGA (STOP)
UUG (Leu)
UCG (Ser)
UAG (STOP)
UGG (Trp)
CUU (Leu)
CCU (Pro)
CAU (His)
CGU (Arg)
CUC (Leu)
CCC (Pro)
CAC (His)
CGC (Arg)
CUA (Leu)
CCA (Pro)
CAA (Gln)
CGA (Arg)
CUG (Leu)
CCG (Pro)
CAG (Gln)
CGG (Arg)
AUU (Ile)
ACU (Thr)
AAU (Asn)
AGU (Ser)
AUC (Ile)
ACC (Thr)
AAC (Asn)
AGC (Ser)
AUA (Ile)
ACA (Thr)
AAA (Lys)
AGA (Arg)
AUG (Meth / START)
ACG (Thr)
AAG (lys)
AGG (Arg)
GUU (Val)
GCU (Ala)
GAU (Asp)
GGU (Gly)
GUC (Val)
GCC (Ala)
GAC (Asp)
GGC (Gly)
GUA (Val)
GCA (Ala)
GAA (Glu)
GGA (Gly)
GUG (Val)
GCG (Ala)
GAG (Glu)
GGG (Gly)
U
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
Amino Acid
Abbreviation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Alanine
Arginine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Serine
Threonine
Tryptophan
Tyrosine
Valine
Ala
Arg
Asn
Asp
Cys
Glu
Gln
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Ser
Thr
Trp
Tyr
Val
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
TRANSLATION
1. mRNA binds to a ribosome and begins to
interpret the message
2. mRNA information is read in groups of three
letters = CODON
3. transfer RNA (tRNA) binds to each codon of
mRNA
has corresponding ANTICODON
other side has A.A. which joins to form
proteins at ribosome
The information of the messenger RNA (mRNA)
describes which amino acids should be in the
protein chain.
A molecule of transfer RNA (tRNA) will carry in
the proper amino acid, one at a time.
A
A.
m
R
N
A
Amino acid
m
R
N
A
A different set of three mRNA subunits means a different
tRNA molecule. That means a different amino acid will be
Carried in.
Two different
Amino acids
Two different tRNA molecules
m
R
N
A
The next tRNA will
Carry in the proper
amino acid
and the process will
continue.
The chain of amino acids is
called a ‘polypeptide’
And when it is very long it is
called a protein.
polypeptide
A polypeptide chain
• Even this is a very, very short polypeptide chain.
Most have hundreds or thousands of amino acids.
A very short polypeptide chain, or part of a protein
DNA thread
TRANSCRIPTION
RNA
Codon
TRANSLATION
Polypeptide
Amino acid
TYPES of RNA
NAME
FUNCTION
Messenger
RNA (mRNA)
Copies info from DNA and takes info
to ribosome
Transfer RNA
(tRNA)
Translates messages from mRNA and
has a complementary codon =
ANTICODON and carries
corresponding a.a.
Ribosomal RNA
(rRNA)
RNA entangled with proteins which
serves as an anchor for translation
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
DNA
A polymer made of
MONOMERS called
Is formed from:
Is made by an P
ENZYME called
R
SUMMARY
N
RNA
There are
3 TYPES called
Happens in a
ORGANELLE called
And with proteins they form
PROTEINS
POLYMER formed from
MONOMERS called
ENZYMES
= biological catalyst
Usually end in
–ASE
( e.g. primase, polymerase, etc)
CATALYST = substance that speeds up a reaction
DNA info
= 6 billion nucleotide pairs
= 1400 biology textbooks
copied in a few hours because of enzymes
Therefore, many enzymes and proteins needed.
DNA REPLICATION
ORGIN OF REPLICATION (OR)
= short specific sequence of DNA nucleotides where
replication of a chromosome begins
=
Recognized by proteins that initiate replication
separates strands and opens replication bubble
DNA replicated in both directions
Thousands of OR bubbles open at same time
strands eventually fused
DNA REPLICATION
REPLICATION FORKS
= Y shaped region at end of bubble where parental strands of DNA are
unwound
Helicase
untwists double helix at replication
Separates parental strand
Topoisomerase
Relieves strain by breaking, swivelling and rejoining DNA strands
Primase
Synthesizes short RNA primer used to begin DNA synthesis
DNA Polymerase III
Elongates primer and then existing chain by adding
nucleotides in 5´ to 3´ direction to complete new DNA
LEADING STRAND
= strand elongated continuously from primer towards fork
LAGGING STRAND
= strand elongated discontinuously away from fork
each has a primer
OZAKI FRAGMENTS
= segments of lagging strands
DNA Ligase
joins Ozaki fragments
TRANSCRIPTION
1) RNA Polymerase
•separates 2 DNA strands
•joins RNA nucleotides in 5´ to 3´direction complementary to
DNA
doesn´t need primer
PROMOTOR Signals where transcription begins
TERMINATOR Signals where transcription ends
TRANSCRIPTION UNIT area transcribed
TRANSCRIPTION
RNA SPLICING
= interspersed coding regions are removed from long regions of
noncoding regions
= cut and paste
EXONS - coding regions later translated into a.a.
INTRONS – noncoding regions between coding regions
SPLICEOSOME – complex that cuts out introns and puts
them together
RIBOZYMES – RNA that functions as enzymes
e.g. some introns, ribosomes
MUTATIONS
= changes to genetic information of a cell
GENETIC DISORDER
= if mutation has adverse affect on phenotype
SUBSTITUTION = replacement of one nucleotide
a) SILENT MUTATION
a.a. does NOT change no effect
b) MISSENSE MUTATION
a.a changes to another no effect or new trait
c) NONSENSE MUTATION
change to STOP codon non-functional protein
INSERTIONS and DELETIONS
FRAMESHIFT disastrous non-functional protein
DNA MUTATIONS
If a mutation in the DNA strand :
•1) changes the base in position 9 to a C
how would this affect the protein ?
•2) changes the base in position 5 to a T
what will the sequence be ?
•3) eliminates the first codon
Which protein will be produced
• 4) eliminates the last codón, what would happen ?
Coding
DNA
Template
DNA
5´
T
A
C
T
C
A
G
A
T
A
T
C
3´
mRNA
codon
tRNA
Anti-codon
A.A.
short name
A.A.
long name
TRANSLATION
Initiation
Enlongation
Termination
